Troubleshooting a Sharp SH-02L :<

I've been having trouble getting signal for a while now, it used to work perfectly in the first couple months, but now it's showing a 'no signal' sign on the top. I checked the band frequency of my network so there shouldn't be any problems with that where I am (Canada). I have no idea have to fix it, pls help i love my phone :,) tyvm!